FR2830293A1 - FAN, PARTICULARLY FOR ROTATING ELECTRIC MACHINES SUCH AS AN ALTERNATOR - Google Patents

Abstract

The invention concerns a fan for an alternator designed to be secured in rotation to the rotor of the alternator comprising a part forming a flange and a plurality of fan-blades (47, 48) extending therefrom, the fan being produced by moulding a plastic material on an insert (50) advantageously made of metal which constitutes the flange part of the fan designed to enable its being fixed on the rotor, and configured to constitute a means for enhancing the mechanical strength of the fan; the insert (50, 65) comprising part of a blade (48, 69) of the fan. The invention is useful for producing a high power cooling fan for a motor vehicle alternator.

Description

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 The invention relates to a fan for rotating electrical machines such as, in particular, an alternator, intended to be secured in rotation to a rotating part such as the rotor of the machine, of the type comprising a flange portion and a plurality of ventilation blades. extending from the latter, the fan being produced by molding a plastic material on a mechanical insert of a material mechanically more resistant than plastic, such as metal, which forms the part of the fan ensuring attachment to the support.

 Fans of this type are already known and described for example in French patent NO 2,673,338 to the applicant. In the fan described in this patent, the insert is made of metal and disposed in the flange-forming part and is used for fixing the fans, in particular by welding, to the rotor. Since the plastic fan is molded on this insert, with its ventilation blades, it is possible to produce fans with blades whose number, configuration and arrangement can be chosen according to the application of the fan and of the cooling efficiency it must provide.

 These fans can be used in machines with a high electrical flow rate which can produce excessive heating under inefficient ventilation.

 These known fans however have the major drawbacks that their manufacture is expensive because of the large quantity of plastic material required which is expensive, and that their mechanical strength is insufficient, also due to the large mass of plastic material used.

 The present invention aims to provide a fan of the type defined above, which does not have the drawbacks which have just been stated.

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 With a view to achieving this aim, a fan is provided according to the invention, in particular for rotary electrical machines such as an alternator, intended to be secured in rotation to a rotating support part, such as the rotor of the machine, of the type comprising a flange part and a plurality of fan blades extending from the latter, the fan being produced by molding a plastic material on an advantageously metallic insert which constitutes the part of the fan flange, intended to ensure its attachment to the support, in which the insert constitutes a frame capable of withstanding the mechanical stresses produced during the rotation of the fan, in order to increase the mechanical strength of the latter.

Thus the molded fan has a reinforced mechanical strength thanks to the metal insert which consolidates the plastic part of the fan. Similarly, the cost of the overmolded fan is reduced because the insert occupies a relatively large space to ensure this good mechanical strength, the amount of plastic required to obtain the overmolded fan becomes less, while ensuring the shape, the arrangement and the desired number of blades.

 The invention is advantageously supplemented by the following different characteristics taken alone or in all their technically possible combinations: - the insert extends over at least substantially the entire extent of the flange portion of the fan.

 Thus, good mechanical strength of the fan is ensured with a reduced amount of plastic, the volume of the flange being essentially occupied by the insert.

 - The insert extends radially over at least two thirds of the molded part of the fan.

 Thus the mechanical strength of the circumferential end of the fan is ensured because this

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 part of the fan that is not overmolded remains very close to the end of the insert, which greatly reduces the mechanical stresses applied to this external part of the fan during its operation in rotation.

- The insert has at its outer periphery a substantially circular outline.

- The insert has an outline at its outer periphery in the form of teeth.

- The insert includes at least part of a fan blade.

 - The fan comprises two series of blades, a series of short secondary blades, at least one of which is disposed between two main blades, in which the secondary blades are at least partially part of the insert. the main blades are at least partially part of the insert.

Thus, one can have only the large sheet metal blades and the small plastic blades.

- blades of the same series are consecutive.

- The insert is made of folded sheet in the form of a fan comprising at least one secondary or main blade.

 - the fan is centrifugal, centripetal, axial, axial-centrifugal or axial-centripetal.

- the blades or the parts of the blades which are not part of the insert are obtained by overmolding a plastic material on the insert.

- the plastic overmolded blades comprise at least partially at least one secondary blade located between two main blades.

- the surfaces of the insert are at least partially covered with plastic. the secondary blades are at least partly covered with plastic.

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 at least the parts of the insert used to attach the fan to its support are free of plastic.

 - The ventilator is an axial ventilator comprising a flange part, and blades fixed on the external face of the cylindrical part and in that the insert extends at least over the extent of the flange.

 - at least part of the cylindrical part is part of the insert.

 - at least part of at least one blade is part of the insert.

 - The fan is an axial fan comprising a flange portion carrying blades and in that the insert extends at least over the extent of the flange.

 - The metal insert has at least one recess to increase the mechanical strength of the overmolding.

- la figure 2 est une vue sur la face avant d'un ventilateur à deux séries de pales selon l'invention - la figure 3 est une vue de la face arrière du ventilateur selon la figure 2 ; - la figure 4 est une vue en coupe le long de la ligne III-III de la figure 3, les pales ayant été omis ; - la figure 5 est une vue en perspective d'un autre ventilateur à deux séries de pales, susceptible d'être réalisé conformément à l'invention ; - la figure 6 est une vue sur la face avant d'un autre mode de réalisation d'un ventilateur à deux séries de pales, selon l'invention ; The invention will be better understood, and other objects, characteristics, details and advantages thereof will appear more clearly in the explanatory description which follows, made with reference to the appended diagrammatic drawings given solely by way of example illustrating a method of embodiment of the invention and in which: - Figure 1 is an axial sectional view of a standard alternator;

- Figure 2 is a view on the front face of a fan with two sets of blades according to the invention - Figure 3 is a view of the rear face of the fan according to Figure 2; - Figure 4 is a sectional view along line III-III of Figure 3, the blades having been omitted; - Figure 5 is a perspective view of another fan with two sets of blades, capable of being produced in accordance with the invention; - Figure 6 is a view on the front face of another embodiment of a fan with two sets of blades, according to the invention;

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- la figure 9 est une vue similaire à la figure 6 d'une autre version de réalisation du ventilateur selon la figure 6 ; - la figure 10 est une vue en perspective d'un ventilateur axial selon l'invention. - Figure 7 is a top view of the metal insert used in the fan according to Figure 6, before folding the portions intended to form the short blades; - Figure 8 is a view of the insert according to Figure 6, after the production by folding of the short blades;

- Figure 9 is a view similar to Figure 6 of another embodiment of the fan according to Figure 6; - Figure 10 is a perspective view of an axial fan according to the invention.

- Figure 11 is a perspective view of another embodiment of an axial fan.

- Figure 12 is a variant of Figure 3.

- Figure 13 is another variant of Figure 3. Figure 1 is only intended to briefly recall the general structure of an alternator for a heat engine of a motor vehicle, in order to place the invention in context d preferred use.

To understand the invention, it suffices to indicate that the alternator shown essentially comprises a rotor 1 which is here of the claw type surrounded by a stator 2 and mounted for rotation on a shaft 3, the front end of which bears in rotation a drive pulley 5 and the rear end of the non-referenced slip rings belonging to a manifold 6. The rotor 1 comprises two pole wheels designated by the references 8a and 8b. The reference number 9 designates the excitation winding of the rotor.

With regard to the stator, it suffices to indicate that it comprises a body 11 internally provided with notches for the passage of wires or pins of the windings 12 of the stator. The motor shaft 3 is supported by front 14 and rear 15 ball bearings provided in bearings respectively before 17 and rear 18. The reference 16 designates the conventional device for

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 16 'diode rectification of the alternating current produced by the machine.

 It is important to note that the alternator comprises front and rear fans 19 fixed in rotation on the front faces respectively of the front pole piece 8a and the rear pole piece 8b.

Each fan has a flange part 21 applied and fixed to the front face of the pole piece of support and a plurality of blades 22. These fans which therefore extend in the vicinity of the front bearing 17 and the rear bearing 18 have the function of create a circulation of a cooling fluid, in this case air, to cool the hottest active parts of the alternator such as the diodes 16 'of the rectifier 16, the bearings 14,15, the winding of the rotor 1 and the windings 12 of the stator, passing through different appropriate openings in the bearings, as illustrated by arrows.

 It is obvious that the more the electrical flow rate of the alternator increases, the higher the cooling capacity of the fans. This increase in the electrical flow of the rotating machine is sought without increasing the volume of the machine. This objective is achieved by an appropriate configuration of the blades.

 Figure 2 illustrates a fan that is designed for this purpose. It has the general reference 24. This fan has a substantially planar circular flange portion denoted 25 which is provided with a circular central opening 27 for the passage of the alternator motor shaft, indicated at 3 in FIG. 1, and two series of ventilation blades, to have a first series of long main blades 29 and a second series of shorter secondary blades 31, each arranged between two long blades 29. Thus each secondary blade 31 is disposed in the ventilation channel 33 formed between the two adjacent long blades 29 and

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 which widens from the inner periphery to the outer periphery of the blades. The shorter secondary blades 31 are located radially above the internal periphery of the long main blades 29. They aim to reduce the noise of the electric machine while increasing the flow rate and the efficiency.

The installation is done in such a way that the secondary blade compresses the cooling fluid so that it is in contact with the main blades 29.

 Of course, one could also envisage different combinations of arrangements of the secondary blades 31 with the long main blades 29.

Thus, one could have several secondary blades 31 between the main blades 29. The number of secondary blades disposed between the main blades, within the same fan can be constant or variable.

Thus for example, for the same fan, it is possible to insert, for example, four secondary blades between two main blades, then three secondary blades between two other main blades or any other combination.

Also, it is conceivable to have several main blades 29 consecutive without secondary blades between them. The distribution of the secondary and main blades is determined according to the electric machine to be cooled in order to obtain the best cooling with minimum aerolic noise.

 The main blades 29 can be distributed angularly in a regular manner or, as in the case shown in FIG. 2, in an irregular manner. The irregular arrangement further reduces operating noise from the fans. It is the same for the secondary blades which can have an irregular angular distribution.

 Figure 5 illustrates in a perspective view a fan of the type according to Figure 2 where at least some of the main blades 29 are provided, overhanging relative to the bottom of the channels 33, with a fin

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 36 extending perpendicularly or inclined with respect to the blades 29, in order to avoid secondary circulation of the fluid above these blades.

 The fans of complex structure as shown in Figures 2 and 5 can of course be made by plastic molding. But as explained above, this manufacturing method has the major drawbacks that the fans have a high cost price and insufficient mechanical strength.

 To overcome these drawbacks, the invention proposes to produce the fans according to FIGS. 2 to 11.

 Figures 2 to 4 illustrate a first embodiment of the invention. Figures 3 and 4 show the flange 25 of the fan, the blades not being visible, which is made of plastic and has an insert 38 whose shape emerges from the sectional view of Figure 3, made along the line III-III of Figure 3.

 The insert extends over practically the entire extent of the flange, the plastic being overmolded on this insert.

 The metallic insert must allow the fan to withstand mechanical stresses produced during rotation of the fan, such as shear, vibration, torsion, bending and elongation stresses. These mechanical stresses produced during rotation cause deformations of the fan, essentially of the plastic part which is not molded onto the metal insert. These deformations can cause mechanical failure of the overmolded part of the fan.

 The insert must therefore have a geometry which makes it possible to perfectly ensure the mechanical strength of the overmolded fan while ensuring a relatively low cost price.

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 In a first embodiment, as shown in FIG. 3, the insert extends over practically the entire extent of the flange, with the plastic material being overmolded on this insert. The dotted line bearing the reference 90 shows the limit of the insert.

 FIG. 12 illustrates another embodiment of the overmolded insert in which it extends radially over at least two-thirds of the overmolded part.

The remaining non-molded part of the fan which is at the outer periphery thus has a radial distance 91 sufficiently small to withstand the mechanical stresses mentioned above.

 It is also possible to use a metal insert which has a non-circular external peripheral limit as shown in FIGS. 3 and 13. Thus, FIG. 13 illustrates an insert whose external and non-circular peripheral limit and is for example in the form of a toothed wheel, these teeth 92 may have a regular shape or not. The geometry of the teeth must be determined in such a way as to ensure the mechanical strength of the fan during its rotation at high speed.

 Also, the metal insert may have recesses 93 to ensure better mechanical strength of the molding. These studs can further reduce the cost of the fan, by performing overmolding on one side of the metal insert. For good mechanical strength, these studs in which the plastic is overmolded must be located so as to ensure good mechanical strength.

 As will be understood, the most economical solution is that shown in FIG. 3 in which the insert occupies essentially the whole part of the flange because it is this configuration which consumes the least plastic, the volume being essentially occupied by the metal insert. The other configurations are also economical compared to the state of the

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 technical because to ensure good mechanical strength, the insert must in all cases occupy a minimum surface that is sufficiently large, that is to say at least greater than the state of the art.

 However, as can be seen from FIG. 3, the insert is locally bare, that is to say not covered by the plastic. The stripped part has the shape of a crown indicated at 39 in FIG. 3 and surrounding the central opening 27. FIG. 4 therefore shows a segment of this crown.

 The crown 39 allows the attachment of the flange 25 to the outer front face of the pole wheel 8a or 8b of the rotor 1 of the electric machine, for example by welding. The circular zones 41 which are distributed, practically angularly equidistant in the example shown (which is not however compulsory), on the crown constitute welding points and correspond to local deformations visible at 43 in FIG. 4 , projecting from the application face of the crown on the pole wheel, all the deformation constituting a welding point. It goes without saying that during the overmolding operation on the insert 38, the blades as shown in FIGS. 2 and 5 will be produced simultaneously. It can be seen that on the front face shown in FIG. 2, the zones indicated at 45 of the insert which are bare are provided for fixing the insert to the rotor. They correspond to the function areas 43 of FIG. 4.

 In the embodiment of the invention, which has just been described, the insert constitutes practically the entire flange part of the fan, thereby giving the latter good mechanical strength. By cons all the blades are made not overmolding.

 FIGS. 6 to 8 illustrate a particularly advantageous embodiment of a fan comprising a design of blades, of the type shown in FIG. 4, that is to say of a fan with two series of

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 blades, namely a first series of long main blades now bearing the reference 47 and a second series of short blades indicated at 48, each disposed between two long blades, as already shown in FIG. 2.

 The particularity of the embodiment according to FIGS. 6 to 8 lies in the fact that the short blades are not obtained by overmolding, but form part of the metal insert now designated by the reference 50.

 FIG. 7 illustrates the insert which is in the form of a sheet metal blank carrying at its periphery cut portions 48 ′ which become, after folding out of the plane of the main part forming the flange part of the fan bearing the reference 51, the short blades 48, as can be seen in FIG. 8. The insert, after folding around an angle of, for example 900, itself already constitutes a fan with short blades.

Of course, the angle could be different from 900, for example for a helical-centrifugal fan.

It can be seen that during the transformation of the flat insert according to FIG. 7 in the fan insert shown in FIG. 8, the blades 48 have been reinforced by ribs 54. It should be noted that the blades 48 are distributed around the flange portion 50 in an irregular manner, the blades being closer to the right in Figures 6 and 8 than on the left side. To complete the description of the insert, there are 56 circular locations provided for fixing the fan to the rotor.

 It is by overmolding plastic material on the insert as shown in FIG. 7 that the fan illustrated in FIG. 6 is produced, with the long main blades 47 which are therefore made of plastic. In FIG. 6, the exterior contour line of the metal insert of FIG. 8 is recognized at 58. In the fan assembly, the metal insert is at

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 bare in each zone 60 around a fixing point 56. Thus the insert can be fixed, for example by welding on the rotor.

 Figure 9 is a partial view of another embodiment of the fan of Figure 8 whose particularity lies in the fact of making more savings in plastic. In fact, in the case of FIG. 9, the short secondary blades 48 are completely disengaged from the plastic, as can be seen in the part designated by the reference 63, which is the outline of the plastic.

 FIG. 10 shows that the principle of manufacturing a fan, according to the invention, makes it possible to obtain other types of fans such as the axial fan shown in this figure. In this case, at least the central flange part 65 is made of metal, the rest with the cylindrical part 67 and the blades 69 being overmolded.

 FIG. 11 shows another type of axial fan which differs from that shown in FIG. 10 by the absence of the cylindrical part 67, the blades 69 being supported by a radially internal support part 70 on the radially external peripheral zone of the flange. As in the case of FIG. 10, at least the central part of the flange is made of metal, the remainder being overmolded. Of course, at least part of at least one blade could be made of metal, for example the support part 70.

 Of course, multiple modifications can be made to the embodiments shown which have been given only by way of example. Thus the blades can be released or be at least partially covered with plastic. The metal insert can be fixed on the rotor not only by welding, but by any other suitable means, for example by riveting, threading, fretage on the shaft, by screws or the like.

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 Unlike the first embodiment described above where the insert does not carry fan blades, and the embodiment according to FIGS. 6 to 8 where the insert already carries one of the two sets of blades, namely short blades, it is possible to use inserts with only one blade or only part of a blade or of several blades or blades of a series of blades.

 Thus, depending on the sheet surface of the insert available for folding the blades, any kind of combination can be made between the blades made of folded sheet metal with the blades made by plastic overmolding. For example, the metal insert can wear long blades only or short blades only or a combination of the two. These blades obviously can be arranged irregularly. Thus the insert can be configured so that it carries only a long or short blade for example.

 In the case of the axial fan according to FIG. 10, the annular part forming the cylindrical rim could also be part of the metal insert, at least in part. One could also additionally provide on the insert at least one primer of the blades, the rest of these will then be produced by overmolding. Of course, the invention allows the production of any other type of fan, in addition to centrifugal and axial fans, such as centripetal, axial-centrifugal or axial-centripetal fans.

 It should be noted that the invention provides an effective solution to the problem posed by fans to be used in rotating electrical machines of high electrical flow, with however the constraint of not increasing the volume. The solution of making the fans only by plastic molding has the disadvantage of an expensive manufacturing process, and that the fans thus obtained do not have the desired mechanical strength.

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 Regarding the manufacturing process for fans made of folded sheet metal, which would be appropriate from the point of view of cost and mechanical strength, it does not allow the configuration of blades which can provide a necessary cooling efficiency, that is to say say two sets of blades in accordance with Figures 2,5 and 6.

 It follows from what proceeds that the invention, in particular in its embodiment which uses a metal insert already in the form of a fan or with at least one blade, allows the production of fans having configurations of complex blades giving them a increased cooling power, at a relatively low cost price while having good mechanical strength.

 For fans having a single series of blades, but which are very close together and thus in large number, or blades of long or complicated shape, and which therefore cannot be produced by folding, part of the fan can then be made in sheet metal and another in plastic.

 Of course, the fans according to the invention, as described and shown, can be used on any type of rotating electrical machine, for example in automobiles, and consumer products, such as vacuum cleaners or the like, but also on compressors and air conditioners.

Claims (22)

1. Fan in particular for rotating electrical machines such as an alternator, intended to be secured in rotation to a rotating support part, such as the rotor of the machine, of the type comprising a flange portion and a plurality of fan blades extending from the latter, the fan being produced by molding a plastic material on an advantageously metallic insert which constitutes the part of the flange of the fan, intended to ensure its fixing on the support, characterized in that the insert ( 38.50, 65) constitutes an armature capable of withstanding the mechanical stresses produced during the rotation of the fan, in order to increase the mechanical strength of the latter.  2. Fan according to claim 1, characterized in that the insert (38.50, 65) extends over at least substantially the entire extent of the flange portion of the fan.  3. Fan according to claim 1, characterized in that the insert (38.50, 65) extends radially over at least two thirds of the molded part of the fan.  4. Fan according to any one of the preceding claims, characterized in that the insert (38.50, 65) has at its outer periphery a contour (90) substantially circular.  5. Fan according to any one of the preceding claims, characterized in that the insert (38.50, 65) has at its outer periphery a contour (90) in the form of teeth (92).  6. Fan according to any one of claims 1 to 5 characterized in that the insert (50, 65) comprises at least part of a blade (48,69) of the fan. <Desc / Clms Page number 16>  7. Fan according to claim 6, characterized in that it comprises two series of blades, a series of short secondary blades (48), at least one of which is disposed between two main blades (29,47), characterized in that the secondary blades (48) are at least partially part of the insert (50).  8. Fan according to claim 6, characterized in that it comprises two series of blades, a series of short secondary blades (48), at least one of which is disposed between two main blades (29,47), characterized in that the main blades (29,47) are at least partially part of the insert (50).  9. Fan according to claim 7 or 8, characterized in that blades of the same series (48, 29,47) are consecutive.  10. Fan according to claim 4, characterized in that the insert (50) is made of folded sheet in the form of a fan comprising at least one secondary blade (48) or main (29,47).  11. Fan according to one of claims 1 to 5, characterized in that it is a centrifugal, centripetal, axial, axial-centrifugal or axial-centripetal fan.  12. Fan according to one of claims 1 to 6, characterized in that the blades (29,31, 47,48, 69) or the parts of the blades which are not part of the insert are obtained by overmolding of a material plastic on the insert.  13. Fan according to claim 12, characterized in that the blades (29,31, 47,48, 69) overmolded in plastic comprise at least partially at least one secondary blade (48) located between two main blades (29,47) .  14. Fan according to any one of the preceding claims, characterized in that the <Desc / Clms Page number 17>  surfaces of the insert are at least partially covered with plastic.  15. Fan according to claim 7, characterized in that the secondary blades (31,48) are at least partly covered with plastic.  16. Fan according to any one of the preceding claims, characterized in that at least the parts (39) of the insert used for fixing the fan on its support are free of plastic.  17. Fan according to one of claims 1 to 10, characterized in that it is an axial fan comprising a flange part (65), and blades (69) fixed on the outer face of the cylindrical part (67) and in that the insert extends at least over the extent of the flange (65).  18. Fan according to claim 17, comprising a flange provided with a cylindrical outer rim, characterized in that at least part of the cylindrical part (67) forms part of the insert.  19. Fan according to one of claims 17 or 18, characterized in that at least part of at least one blade (69) is part of the insert.  20. Fan according to one of claims 1 to 10, characterized in that it is an axial fan comprising a flange part (65) carrying blades (69) and in that the insert extends at least over the extent of the flange (65).  21. Fan according to claim 20 characterized in that at least a part of at least one blade (69) is part of the insert.  22. Fan according to one of the preceding claims, characterized in that the metal insert (38.50, 65) comprises at least one recess (93) to increase the mechanical strength of the overmolding.